In a piece about the programme, the Channel 4 Dispatches website said a reporter had attended talks at mosques and found preachers "condemning the idea of integration into British society, condemning British democracy as un-Islamic and praising the Taliban for killing British soldiers".

Police said they acknowledged some parts of the programme may have been considered offensive, but, when analysed in full context, there was not enough evidence to bring charges.

'Completely distorted'

The police investigation was extended to include looking at issues relating to the editing of the programme.

Crown Prosecution Service (CPS) lawyer Bethan David scrutinised 56 hours of media footage, only some of which was used in the broadcast.

She said: "The splicing together of extracts from longer speeches appears to have completely distorted what the speakers were saying.

"The CPS has demonstrated it will not hesitate to prosecute those responsible for criminal incitement.

"But in this case we have been dealing with a heavily-edited television programme, apparently taking out of context aspects of speeches which in their totality could never provide a realistic prospect of any convictions."

Police asked the CPS to consider a prosecution of Channel 4 under the Public Order Act 1986 for showing material likely to stir up racial hatred, but they were advised there was insufficient evidence.